diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 15705e1..6212cc4 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -10846,7 +10846,7 @@
     assert(p);
     for (i = 0; i < len; i++) {
         unsigned char c = (unsigned char)str[i];
-        if (c > 128 || p[i] != (wchar_t)c)
+        if (c >= 128 || p[i] != (wchar_t)c)
             return 0;
     }
     return 1;